PROJECT SUMMARY. Young adult sexual minority women (SMW), including lesbians and bisexuals, are at particularly high risk, with up to 4.8 times increased odds of cigarette smoking than heterosexual women; up to 660,000 young adult SMW smoke and are at increased risks of smoking-related cancers and cardiopulmonary illnesses. Exposure to tobacco industry marketing, minority stressors, alcohol and drug use and social determinants are key factors linked to increased smoking behavior in this population. Anti-smoking campaigns utilized inoculation messages (analogous to vaccines) and culturally-tailoring (i.e., LGBT imagery, symbols, and language) to promote resilience against tobacco marketing influences among LGBT audiences. However, the effects of culturally tailored inoculation approaches in young adult SMW have not yet been examined. Our long-term goal is to eliminate smoking-related health disparities among LGBT populations. The objectives of this study are to determine the effects of using a culturally-tailored inoculation approach to increase resilience to tobacco marketing influences among young adult SMW and obtain stakeholders' critical inputs that support later adoption and implementation. Our central hypothesis is that culturally tailored inoculation messages addressing unique perspectives of young adult SMW will be more effective versus non-tailored messages to increase resilience to tobacco marketing. The scientific premise is supported by 1) campaigns promoting resilience against tobacco companies and smoking among LGBT audiences, 2) our pilot study showing young adult SMW perceive higher relevance, favorable attitudes, and positive emotions toward LGBT imagery compared to control imagery, and 3) an integrative conceptual framework informed by communication science, the minority stress framework, and the socioecological model of resilience factors among SMW. Our specific aims are: 1) Engage with key stakeholders to optimize message construction and collect pilot data to inform future intervention design, 2) Evaluate the effects of culturally tailored anti-smoking messages on young adult SMW's smoking and quitting intentions, and 3) Evaluate the effects of inoculation message type, dose, and latency on young adult SMW's resilience to tobacco marketing, smoking and quitting intentions. We will conduct twice-yearly meetings, rapid cycle feedback, and key informant interviews with an Expert Advisory Committee comprising LGBT organization leaders, investigators in sexual and gender minority health, community members, and national agencies (NCI, CDC, and FDA); message development and testing using qualitative research methods; and randomized survey experiments. Impact: Findings from this study will provide the foundation to develop an evidence-based and culturally tailored inoculation approach to increase resilience to tobacco marketing among young adult SMW and that addresses the needs of future adopters and implementers. The study methods and findings will further inform research on counter-marketing interventions to reduce smoking-related health disparities among all sexual and gender minority populations.